Modified lubricating oils



Patented Oct. 31, 1944 UNITED STATES PATENT OFFICE Moon-inn LUBRICATING OILS No Drawing. Application June 6, 1939, Serial No. 277,877

8 Claim.

This invention relates to modified mineral lubricating oils specially adapted for use in .Diesel engines and other severe service internal combustion engines in which the oils are subjected to heavy service.

In Diesel engines and similar engines the high temperatures developed tend to act upon the lubricating oils to cause the deposition of resinous and varnish-like'materials whichin turn tend to cause ring and valve sticking and to produce lacquer-like coatings on the pistons and elsewhere and interfere with engine operation. In eiforts to overcome these diiilculties various types of metal soaps of fatty acids and the like have been introduced which act as detergents to prevent the deposition of such resinous and varnish-like materials or to remove such materials. In general, the metal elements of these soaps apparently have tended to function to some extent as oxidation catalysts with the result that corrosive acid conditions have been formed in the engines causing corrosion of the highly sensitive type of bearings such as cadmiumsilver and copper-lead bearings. In the case of copper-lead bearings the lead has actually been leached out from the portions adjacent the moving parts to leave a somewhat spongy weakened copper bearing face.

The principal object of the present invention is to overcome these catalytic oxidation conditions and also to neutralize acids which may be produced by oxidation. The present invention resides in mineral lubricating oils containing soaps of weak non-carboxylic organic acids which will act as anti-oxidants rather than oxidation catalysts, and which may possibly neutralize stronger acids produced by oxidation.

Such weak organic acid materials are of the non-carboxylic acid type, being of the type represented by phenols and their derivatives which possess weakly acidic properties and are saponifiable. A specific usable phenolic material of which I have produced the calcium salt is di-ptertamyl diphenol sulfide which apparently has the formula:

1) CH: CH3.CH2- Qs-Q-dcmcm I n no hm CH:

A more suitable phenolic material, however, is obtainable on the market under the trade name Paranox" which apparently is in general composed of mixed poly-alkyl poly-phenol sulfides,

that is, poly-alkyl substituted hydroxy phenyl thio ethers, containing for example a thio ether of butyl phenolate which may be designated as bis (2-hydroxy-4-butyl phenyl) sulfide. This commercial product apparently contains various materials of the following general formulas: V

R (canon) s (canon) R R(CeI-EOH) S(CeH2OH) R- S(CsHaOI-I) R In these formulas and similar formulas herein S in general indicates one sulfur atom, but in some molecules two or more sulfur atoms may be represented, the major proportion, however, being the possibly preferred monosulfides; R is an alkyl group preferably containing 4 or 5 carbons (but may'contain more) which groups maybe different for the difierent components of the mixture or may be different for the two or more benzene nuclei in one of the components. R, S and OH may occupy any of the possible positions in the benzene rings. Conveniently, the alkyl groups are butyl or amyl group such as tertiary butyl or amylgroups, and the phenolic materials are mixed phenols, for example, petroleum refinery cresols or crude coal tar phenols. The materials may contain higher polymers such as indicated in the second formula above, and even more extensively polymerized materials. The salts of these materials may properly be considered soaps. When about 1% of such a suitable oil-soluble soap, such as the calcium soap, (or between about three-quarters of 1% and about 2%) is dissolved in mineral lubricat ing oil, it has the combined effect of imparting to the mineral lubricating oil, where intended for severe service internal combustion engines, the required detergency characteristics and at the same time of acting apparently as an antioxidant or at least in some manner as an inhibitor of the formation of corrosive conditions.

The invention, therefore, also resides in the use of oil-soluble metal salts or soaps of the indicated phenolic type 01' sulfur-bearing acidic materials, particularly calcium soaps. It also' tralization.

cording to this invention may be found in a ditertiary-butyl diphenol sulfide as his (2-hydroxy-4 tertiary butyl phenyl) sulfide having the structural formula:

oHmoO-sQ-cwum The calcium soaps produced therefrom may be considered as representative soaps for addition to lubricating oils according to this invention and apparently have the structural formulas:

HICdQBQCIHI Ca and I HMO-SO! 0 HO- Ala t H O HaCcOS-O-CJII In the phenol sulfide formulas given above where the alkyl group is indicated as being in para position to the sulfur, it may be that the alkyl group is best represented as being in para position to the hydroxy position.

In practicing the invention commercially the soaps of suitable phenolic compounds, such as the calcium soap of dibutyl or other alkyl or mixed alkyl phenol sulfides above indicated, may be formed without particular difilculty by any suitable neutralization procedure as will be obvious to the skilled chemist. For example, suitable mixed alkyl phenol sulfides now available on the market as Paranox" as above indicated are furnished with about 80% of a lubricating oil mixture. To this material is added an approximately equal quantity of a suitable lubricating oil, such as a naphthenic base mineral lubricating oil having good solvent properties for the phenol and for the soap to be produced. This oil mixture is then commingled with hydrated calcium oxide and a small proportion of water, followed by heating to about 300 F. with agitation for a time to insure neu- The resultant mixture is filtered to remove solids such as excess calcium oxide.

In order to increase the ash- (i. e. calcium content) it has been found convenient first to heat only-to about 200 F. to 210 F. for a time to insure complete admixture and partial neutralization, then cool to 150 F. to 170-F., add a small quantity in the order of 3% of 95% alcohol, and then raise to the mentioned temperature of 300 F.

Another method to form the soap is to neutralize the butyl phenol sulfide with sodium hydroxide and then by metathesis with calcium chloride or the like convert the soap to the calcium soap. This saponification or neutralization may be more or less readily accomplished inasmuch as the pure material has been found to have an acid number of about'98.

The soaps described are readily soluble in lubricating oils in the required proportions to yield alkaline rather than acid solutions.

Other materials which might be used for some purposes in place of the indicated thio-ether of butyl phenolates would be the ether itself, and corresponding thio-ethers having shorter chains than the butyl group where sufficiently oil-soluble or probably preferabl longer chains in orderto possess adequately high molecular weight and insure good oil solubility. Carboxylie acid substituents are excluded. Phenolics presenting only one ring would require aliphatic chain or appreciable length in order to impart sufllcicntly high oil solubility.

In preparing Diesel engine lubricating oil according to the present invention the soap, or the soap-oil mixture, is stirred into an appropriate mineral lubricating oil and solution is effected by agitation, a slight elevation of temperature being produced if desired to facilitate the solution operation.

When the calcium soap is dissolved in the lubricating oil to yield in the final product a soap content in the order of about 1% to 1.5% or between limits of approximately 0.75% and 2%, the detergent action of the resultant lubricating oil is sufllcient to overcome or prevent the deposition of the objectionable amounts of said resinous and varnish-like materials above mentioned, and at the same time this quantity of soap is insufficient to substantially increase the original viscosity of the base mineral lubricating oil. Not only do the calcium soaps of these alkyl phenol thio-ethers produce such desir'ed detergency and thereby prevent sticking of rings and valves and the deposition of varnish-like coatings, but at the same time they prevent the formation of objectionable corrosive acid conditions which attack materially the highly corrosivesensitive alloy bearings of the copper-lead type. Kindred phenolic compound soaps not of the carboxylic acid type, when amply oil-soluble, especially calcium soaps, may be substituted for some uses where they act as anti-oxidants.

Preferably, the mineral lubricating oil is of a type which does not in itself tend readily to produce corrosive conditions. Such an oil is a western type or naphthenic base mineral lubricating oil, and it may contain substantial amounts of naturally-occurring sulfur such as mineral lubricating oils produced from the high sulfur Santa Maria Valley (California) stocks or the Smackover (Arkansas) stocks and the like. However, it may be possible for some uses to employ parafllnic type oils where the indicated soap, or the quantity of such, soap, is such as to overcome or prevent the formation of corrosive conditions as stated.

In addition to the general functions of a soap which are imparted to the oil by the calcium soap here described, the presence of the sulfur in the soap molecule also tends to impart to a non-sulfur oil extreme pressure characteristics, and the small percentage of actual sulfur present in the soap further acts to impart in itself some anti-corrosive properties.

In addition to calcium soaps of the phenol ethers indicated, soaps of other light metals of some of the alkylated phenol ethers may be employed, particularly the other alkaline earth metal magnesium and also zinc and aluminum, the important requirements being good solubility in the chosen mineral lubricating oil and good detergent properties and freedom from appreciable viscosity increase when used in detergent quantities such as the indicated range of about .75% to 2%. Also the mentioned metals appear to possess less catalytic activity than heavier metals such as lead. Soaps of other phenol ethers such as alkyl-substituted phenol selenium or tellurium ethers or the like containing other 4 proved by incorporating into the suitable suli'ur substitutes in the ether position are also within the'scope oi this invention (orin oil and adequate detergent properties.

Another type of substituted phenolic material which will yield soaps having some value at least for some uses are formaldehyde condensation type products with alkyl-substituted phenols such as amyi phenol. In preparing these phenolics, the anti-oxidant property may be imphenol originally used some additional anti-oxidant constituent such as an amine group. For example, another material could be added such as an amino phenol or benzylarninophenol or a portion of a polyhydroxyphenol such as hydroquinone or catechol. All the usable soaps herein disclosed will possess to a greater or lesser degree the anti-oxidant properties desired. It may be that they will in some part combine with the stronger oxidation acids formed in the lubricating oil when used in engines and release some or the weaker phenols, but it is not desired to be bound by such theory.

It is to be understood that these disclosures are given as illustrative of the generic invention within the scope of the appended claims rather than as limiting thereof.

I claim:

l. A method for the manufacture of detergent mineral lubricating oil comprising combining an oil-soluble alkylated phenol ether with a quantity of mineral lubricating oil, the chemically equivalent amount of an oxide of a light weight metal selected from the class consisting of calcium, magnesium, zinc and aluminum and a small proportion of water, agitating the mixture and heatingto a temperature 01' about 200 F. to 210 F. to insure complete admixture and partial neutralization, cooling the batch to about 150 F. to 170 F., adding a small quantity in the order of 3% of approximately 95% alcohol and raising the temperature of the batch to about 300 F. with agitation and maintaining the batch at approximately 300 F. for a sufficient time to insure neutralization, said oil-soluble alkylated phenol ether being an ether selected from the class consisting of thlloethers, selenium ethers and tellurium'ethers.

2. A method for the manufacture of detergent mineral lubricating oil comprising combining an oil-soluble alkylated phenol ether with a quantity of mineral lubricating oil, the chemically equivalent amount of hydrated calcium oxide and a small proportion of water, agitating the 7 mixture and heating to a temperature of about 200 F. to 210 F. to insure complete admixture and partial neutralization, cooling the batch. to about 150 F. to 170 F., adding a small quantity in the order of 3% of approximately 95% alcohol and raising the temperature oi the batch to about 300 F. with agitation and maintaining the batch at approximately'300" F. for a sufilcient time to insure neutralization, said oilsoluble alkylated phenol ether being an ether selected from the class consisting or thioethers, selenium ethers and telluriurn ethers.

3. A method for the manufacture of detergent mineral lubricating oil comprising combining an oil-soluble alkylated phenol thdoether with a quantity of mineral lubricating oil, the chemically equivalent amount of an oxide of a light weight metal selected from the class consisting of calcium, magnesium, zinc and aluminum and a small proportion of water, agitating the mixture and heating to a temperature of about 200 F. to 210 F. to insure complete admixture and partial neutralization, cooling the batch to about 150 F. to 170 1",, adding a small quantity in the order or 3% of approximately alcohol and raising the temperature of the batch to about 300 F. with agitation and maintaining the batch at approximately 300 F. for a suiflcient time to insure neutralization.

4. A method for the manufacture of a detergent mineral lubricating oil comprising combining an oil-soluble compound having the formula mcun'omswirnoma where R is an alkyl radical containing at least 4 carbon atoms and S represents an element 01' the class consisting of sulfur, selenium and tellurium with a quantity of mineral lubricating oil, commingling the mixture with approximately the chemical equivalent of an oxide of a light weight metal selected from the class consisting of calcium, magnesium, zinc and aluminum and a small proportion of water, heating the batch to around 200 F. to 210 F. for a time to insure complete admixture and partial neutralization, cooling the batch to around 150 F. to 170 F., adding a small quantity. in the order 01. 3% oi approximately 95% alcohol, and raising the temperature of the batch to around 300 F. with agitation and maintaining the batch at approximately said 300 F. for sufilcient time to insure neutralization, and filtering to remove solids.

5. A method for the manufacture of a detergent mineral lubricating oil comprising combining an oil-soluble compound having. the formula Rabi-B) s (canon R where R is an alkyl radical containing at least 4 carbon atoms and 8 represents an element of the class consisting of sulfur. selenium and tellurium with a quantity of mineral lubricating oil, commingling the mixture with approximately the chemical equivalent of hydrated calcium oxide and a small proportion of water, heating the batch to around 200 F. to 210 F. for a, time to insure complete admixture and partial neutralization, cooling the batch to around F. to F., adding a small quantity in the order or 3% of approximately 95% alcohol, and raising the temperature of the batch to around 300 F. with agitation and maintaining the batch at approximately said 300 F. for sufilcient time to insure neutralization, and filtering to remove solids.

6. A method for the manufacture of a detergent mineral lubricating 011 comprising combining an oil-soluble compound having the formula R(CcIL10H) S(CsH3OH) R where R is an alkyl radical containing at least 4 carbon atoms and 8 represents sulfur with a quantity of mineral lubricating oil, commingling the mixture with approximately the chemical equivalent of hydrated calcium oxide and a small proportion of water, heating the batch to around zation, and filtering to remove solids.

7. A method for the manufacture of a detergent mineral lubricating oil comprising combining an oil-soluble alkylated phenol thioether with a quantity or mineral lubricating oil, cornmlngling the mixture with approximately the chemical equivalent of hydrated calcium oxide and a small proportion of water, heating the batch to around 200 F. to 210' I". for a time to insure complete admixture and partial neutralization, cooling the batch to around 160 F. to 170 F., adding a small quantity in the order 0! 3% or approximately 95% alcohol. and raising the temperature of the batch to around 300 1". with agitation and maintaining the hatch at approximately said 300' l". for suflicient time to insure neutralization, filtering to remove solids and adding to said batch sumcent additional mineral lubricating oil to produce a detergent mineral lubricating oil containing between about 0.75% and 2.0% by weight 0! the calcium soap 0! said oil-soluble alkylated phenol thioether. go

8. A method for the manufacture of a detergent mineral lubricating oil comprising combining an oil-soluble alkylated phenol thioether with a quantity of mineral lubricating oil, commingling the mixture with approximately the chemical equivalent of hydrated calcium oxide and a small proportion 01 water, heating the batch to around 200' I". to 210 F. for a time to insure complete admixture and partial neutralization. cooling the batch to around 150 F. to 170 1",, adding a small quantity in the order oi 3% of approximately 95% alcohol, and raising the temperature oi! the batch to around 300 F. with agitation and maintaining the batch at approximately eaid 300 F. for suflicient time to iniure neutralization, and filtering to remove so da.

CHESTER I WILSON. 

